Timing interface module with daughter timing reference modules

ABSTRACT

A timing interface module with daughter timing reference modules. The timing modules are provided in a rack platform to eliminate routing problems and which is compliant with all relevant industry standards. The timing reference module includes a face plate having first and second substantially rectangular openings, the face plate further comprising mounting slots for receiving mounting hardware therein and first and second timing modules, the first and second timing modules disposed within the first and second substantially rectangular openings. The first and second timing modules provide timing terminations for timing reference signals for network elements of a synchronized optical network.

BACKGROUND

The present invention relates to systems and methods for networkcommunications. More particularly, the present invention relates to atiming interface module with daughter timing reference modules.

The increasing use and expansion of digital voice, TV and Internetservices continue to apply pressure for increased bandwidth. In fact,even more bandwidth-intensive services are on the horizon. Thisincreased demand means service providers need to add capacity to theirnetworks as quickly as possible. Previously, that process required theintegration of additional hardware or even the complete replacement ofexisting networks because a service provider's network typically onlyallows so much data traffic to travel through at any given time.

However, advancements in optical transport systems fully integrateadditional bandwidth capability in easily expandable modules. Moreover,such advancements are allowing providers to increase the bandwidthavailable on their existing networks without extensive network redesignor reconfiguration. For example, rather than installing additionalstand-alone hardware, an optical transport system may be used tointegrate pure optical switching via wavelength selective switches,reconfigurable optical add-drop multiplexing, Ethernet switching,next-generation SONET/SDH add-drop multiplexers and dense wavelengthdivision multiplexing (DWDM) into a single platform. Thus, traffic maybe added or dropped into a DWDM network to easily increase bandwidth tooffer HDTV, video-on-demand and high-speed Internet access.

A SONET multiplexer enables carriers to cost-effectively combine signalsof multiple optical carrier levels onto one wavelength for transport.Further, SONET network equipment transports and/or multiplexes trafficthat has originated from a variety of different clock sources. Thus,SONET requires timing sources to provide synchronization. Externaltiming connections provide the timing signals to ensure synchronousaccuracy of the network. In contrast, other types of networks do notrequire timing, e.g., Ethernet, ATM, SAN, etc. For example, legacy DWDMand other data systems do not have external timing connections.

It can be seen then that there is a need for a method and apparatus forproviding external timing to systems for combining synchronous and datasignals while complying with all relevant industry standards.

SUMMARY

Exemplary embodiments address these and other issues by providing atiming interface module with daughter timing reference modules. Timingmodules are provided in a rack platform to eliminate routing problemsand which is compliant with all relevant industry standards.

According to one embodiment, a timing reference module includes a faceplate having a first and second substantially rectangular opening, theface plate further comprising mounting slots for receiving mountinghardware therein and a first and second timing module, the first andsecond timing module disposed within the first and second substantiallyrectangular openings, wherein the first and second timing modulesprovides timing terminations of timing reference signals for networkelements of a synchronized optical network.

These and other features and advantages will be apparent from a readingof the following detailed description and a review of the associateddrawings. It is to be understood that both foregoing general descriptionand the following detailed description are exemplary and explanatoryonly and are not restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a rack mounted optical transport system according toan embodiment;

FIG. 2 illustrates a multiplexer in a SONET network according to anembodiment;

FIG. 3 shows a system using an external timing source; and

FIG. 4 illustrates a timing interface module according to an embodiment.

DETAILED DESCRIPTION

In the following description, reference is made to the accompanyingdrawings that form a part hereof, and in which is shown by way ofillustration exemplary embodiments. It is to be understood thatembodiments are applicable to a timing interface module with daughtertiming reference modules.

FIG. 1 illustrates a rack mounted optical transport system 100 accordingto an embodiment. In FIG. 1, a plurality of components 112, 114, 116 aremounted in a rack 110. According to an exemplary embodiment, components112, 114, 116 of the optical transport system 100 may include an opticaltransmission module, optical repeater module, optical reception module,etc. The optical transport system 100 conducts the processing, such asamplification, repeating, termination, add-drop, etc., with respect tooptical signals. Moreover, a large number of optical cables (opticalfibers) are brought into each optical transmission station that thencarries out the processing, such as amplification, repeating, etc. Aportion of the processed optical signal may be provided to an opticalcable, while the remaining optical signal may be, for example, convertedto an electric signal for transmission as a packet signal.

The amplification, repeating and other processing are conducted in theoptical transport system 100. A plurality of shelves 120 may beconfigured as one unit on one rack to provide for an increase inmounting density of these shelves. The entire equipment in which adesired device works (or operates) in a rack may be referred to as arack mount apparatus.

In FIG. 1, a front view of the optical transport system 100 is shown.Slots 130 are formed in a front surface side of shelf rack 120 so thateach of the slots 130 allows the insertion of a plug-in unit, printedboard unit or package. Connectors 140 may be provided on the front or atthe back of the rack. Components 116 may provide lighted indicators 150on the front to provide an indication of a state for the components 114or to a signal status.

Although the size of a rack is determined according to the industrystandard, for non-standard shelving the size of the shelf 120 may bedesigned to match the size of the rack to achieve the high-densitymounting in one rack. The optical transport system 100 may also includean internal fan unit 160 with a cooling fan, for example, at the base ofthe optical transport system 100.

As mentioned above, advancements in transponder modules have led tofully integrated bandwidth capability in easily expandable modules.Moreover, such advancements are allowing providers to increase thebandwidth available on their existing networks without extensive networkredesign or reconfiguration. With reference to FIG. 1, an opticaltransponder module may be simply plugged into a slot for coupling to anetwork's existing switches of the optical transport system 100 toprovide a dramatic increase in capacity.

A SONET multiplexer may be installed in the rack mount system to enablea carrier to cost-effectively combine signals of multiple opticalcarrier levels onto one wavelength for transport. A timing interfacemodule as described below may be mounted in the shelf 120 to providetiming signals to enable the signals from different clock sources to besynchronized.

FIG. 2 illustrates a multiplexer in a SONET network 200 according to anembodiment. In FIG. 2, three datastreams 210, 212, 214 are shown asinputs to a SONET multiplexor 216. SONET allows datastreams of differentformats to be combined onto a single high-speed fiber optic synchronousdatastream 220. However, combining datastreams of different formatsrequires the connection of external timing source to synchronize thedatastreams. Moreover, the timing source must be compliant with allrelevant industry standards.

FIG. 3 shows a system using an external timing source 300. In FIG. 3, aprimary reference source (PRS) 310 provides signals to a synchronizationsupply unit (SSU) 320. The synchronization supply unit 320 providesprimary 322 and secondary 324 timing signals to equipment, such as anadd/drop multiplexer 330 and telecommunications switch 340. For example,the add/drop multiplexer 330 may be used to combine datastreams 332 ofdifferent formats as described above with reference to FIG. 2. Theswitch 340 may be coupled to a communications network 350, such as acellular network.

FIG. 4 illustrates a timing interface module 400 according to anembodiment. In FIG. 4, the timing interface module 400 is configured formounting in a rack system, such as the rack mount system 100 illustratedin FIG. 1. The timing interface module 400 includes daughter timingreference modules 462, 464. The timing interface module 400 is designedas a circuit pack-like device that is slotted in the shelves of the rackmount system 100 shown in FIG. 1.

The timing interface module 400 may be permanently mounted in the rackmount system 100 of FIG. 1, for example, with four screws throughmounting slots 410-416 in the faceplate 418. The timing interface module400 provides timing terminations for any synchronous components thatmight be mounted in the rack. The timing interface module 400 may alsoinclude wire wrap pins 420 to physically tie down the synchronizationsignals. The wire-wrap pins are recessed and the cover provides strainrelief for the timing cables that are terminated there. External cabling(other than the cables to the SSU) is not are not required. The twoslots may be configured with redundant modules 462, 464 to providecopies of both the primary and secondary timing reference signals to thebackplane 430. Accordingly, the timing interface module 400 provides asolution that will not require any external cabling to make connectionsbetween T1 timing reference termination points and distribution to thebackplane of the rack mount system.

The timing interface module 400 according to an embodiment replaces theneed for a previously required Timing Interface Bracket (TIB) andapplication of power for the timing interface module 400 is madesimpler. In addition, the timing interface module 400 according to anembodiment eliminates the need for any special cables previouslyrequired to interconnect the TIB and timing reference modules (TRMs).The timing interface module 400 may therefore be installed so that anoptical transport system may behave like a SONET NE with respect totiming connections, i.e., as if external timing were an option from thebeginning. The dimensions of the timing interface module 400 may beconfigured to occupy two or more adjacent slots in a shelf of the rackmount system. Captive screws utilizing existing threaded holes in thechassis of the rack and threaded through the mounting slots 410-416 makethe timing interface module 400 a semi-permanent extension of the shelf

Sub-modules 462, 464 are the redundant Timing Reference Modules (TRM)that, as indicated above, provide copies of both the primary andsecondary timing reference signals to the backplane 430. In addition,the sub-modules 462, 464 are easily removable using, for example,thumb-latches 470-476. An insulated metal cover 480 may be provided toprotect wire-wrap pins 420 and provide mechanical strain relief fortiming cables. Recessed wire-wrap pin fields 420 are provided forprimary and secondary BITS clock connections.

Accordingly, the timing interface module 400 enables data and SONETservices to be multiplexed onto a single wavelength. The combining ofdifferent services and data signals of different formats allows serviceproviders to provide additional wavelength services. Additionaladvantages could be realized through cost savings for transport of IOFor other “internal” traffic.

The circuit pack-like device provided by the timing interface module 400serves the same purpose as the backplane timing terminations found onall existing SONET network elements. Wire wrap pins physically tie downthe synchronization signals. Thus, the timing interface module 400eliminates the need for external cabling to make connections between theprimary timing reference termination point and distribution to thebackplane of the shelf.

The above specification, examples and data provide a completedescription of the manufacture and use of the composition of theinvention. Since many embodiments of the invention can be made withoutdeparting from the spirit and scope of the invention, the inventionresides in the claims hereinafter appended.

1. A timing interface module, comprising: a face plate having a firstsubstantially rectangular opening and a second substantially rectangularopening, the face plate further comprising a mounting slot for receivingmounting hardware therein; a timing module disposed within the firstsubstantially rectangular opening, the first timing module receiving areference timing signal and outputting the reference timing signal to aphysical connector on an exterior surface of the face plate; and anoptical multiplexer installed within the mounting slot, the opticalmultiplexer having a timing input connected to the physical connector ofthe timing modules, the optical multiplexer receiving the referencetiming signal, the optical multiplexer also having other inputs thatreceive multiple data streams of different formats, the opticalmultiplexer synchronizing the multiple data streams to the referencetiming signal, the optical multiplexer multiplexing the multiple datastreams into an optical output of one wavelength.
 2. The timinginterface module of claim 1, wherein the mounting slot is configured foralignment with threaded mounting holes in a rack.
 3. The timinginterface module of claim 1, wherein the timing module comprises anotherphysical connector for outputting the reference timing signal to abackplane.
 4. The timing interface module of claim 1 further comprisingwire wrap pins on the exterior surface of the face plate that alsoreceive the timing reference signal.
 5. The timing interface module ofclaim 4, wherein the wire wrap pins are recessed from the exteriorsurface of the faceplate.
 6. The timing interface module of claim 5,further comprising an insulated metal cover for protecting the wire wrappins.
 7. The timing interface module of claim 4, further comprising aninsulated metal cover for protecting the wire wrap pins.
 8. The timinginterface module of claim 1, further comprising a cable having an endconnected to the physical connector on the exterior surface of the faceplate and an opposite end connected to the timing input of the opticalmultiplexer.
 9. The timing interface module of claim 1, furthercomprising a latch that releases the timing module from the face platefor removal.
 10. A system for providing optical transport processing,comprising: a rack for mounting components of an optical transportsystem; a face plate having a first substantially rectangular openingand a second substantially rectangular opening, the face plate furthercomprising a mounting slot for receiving mounting hardware therein; atiming module inserted into the first substantially rectangular opening,the first timing module receiving a reference timing signal andoutputting the reference timing signal to a physical connector on anexterior surface of the face plate; and an optical multiplexer installedwithin the mounting slot, the optical multiplexer having a timing inputconnected to the physical connector of the timing modules, the opticalmultiplexer receiving the reference timing signal, the opticalmultiplexer also having other inputs that receive multiple data streamsof different formats, the optical multiplexer synchronizing the multipledata streams to the reference timing signal, the optical multiplexermultiplexing the multiple data streams into an optical output of onewavelength.
 11. The system of claim 10, wherein the mounting slot alignswith threaded mounting holes in the rack.
 12. The system of claim 10,wherein the timing module comprises another physical connector foroutputting the reference timing signal to a backplane.
 13. The system ofclaim 10, further comprising wire wrap pins on the exterior surface ofthe face plate that also receive the timing reference signal.
 14. Thesystem of claim 13, wherein the pins are recessed from the faceplate.15. The system of claim 14, further comprising an insulated metal coverfor protecting the wire wrap pins.
 16. The system of claim 13, furthercomprising an insulated metal cover for protecting the wire wrap pins.17. The system of claim 10, further comprising a cable having an endconnected to the physical connector on the exterior surface of the faceplate and an opposite end connected to the timing input of the opticalmultiplexer.
 18. The system of claim 10, further comprising a latchethat releases the timing module from the face plate for removal.